The most common mistakes involved painkillers like paracetamol, morphine and diamorphine.

BBC: Patients 'at risk' from drug errors

If the panel's advice is adopted by FDA, it would put hydrocodone on par with prescription painkillers like oxycodone, morphine, and methadone -- drugs with high abuse potential that can lead to severe physical dependence.

CNN: STORY HIGHLIGHTS

In the fourth experiment, researchers gave 21 participants two infusions of a morphine-like drug while they were being scanned and having the heat tests.

WSJ: Doctors use brain scans to 'see' and measure pain

The urge to drink or take drugs is, neurochemically speaking, linked to endorphins (natural morphine-like molecules) or dopamine, a neurotransmitter that is involved in bits of the brain that control reward behaviour.

ECONOMIST: New drugs for old habits

He found a 17-year-old paper written by University of Maryland researcher Paul Mazzochi that mentioned how moving a nitrogen atom in a morphine molecule caused its morphinelike properties to disappear--and also made it poisonous, just like nicotine.

FORBES: Tobacco-Free